





- WITH CHLOROPHYL. 


% 


















REPRINT OF THE AUTHOR'S PRINCIPAL PUBLICATIONS 
ELATING TO THE SUBJECT OF CORRECT-COLOR-TONE 
‘PHOTOGRAPHY, WITH SOME NEW EXPLANATORY 
ae NOTES, EXTRACTS FROM VARIOUS OTHER PUB- fhe 
-LICATIONS, AND A STATEMENT CON.’ 


CERNING A DISCUSSION ABOUT as 
PRIORITY. 














ee. . BY : ry Wee Bde 
 PREDERIC E-IVES..\. 30) loge 





Yt ian fA or a nah Bevis dit 














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‘SSOCHROMATIC PHOTOGRAPHY 


WITH CHLOROPHYL. 


Poem RINT OF THE AUTHOR’S PRINCIPAL PUBLICATIONS 
RELATING TO THE SUBJECT OF CORRECT-COLOR-TONE 
PHOTOGRAPHY, WITH. SOME NEW EXPLANATORY 
NOTES, EXTRACTS FROM VARIOUS OTHER PUB- 
LICATIONS, AND A STATEMENT CON- 

CERNING A DISCUSSION ABOUT 
PRIORITY. 


BY 


i 359 a 8 OE eo A es 





OF Ct OvR Ins a —~ 


QAR OV 
SOF YRIGE oe eo 


er RY 


WASHING 
ae 


PHILADELPHIA: 
PrN ee oY WEE AUTHOR. 


1886. 





EG Pea tee 


When, in 1879, the writer first called attention to the 
possibility of producing correct-color-tone photographs, 
_and published a complete process of isochromatic pho- 
tography with chlorophyl, the process was not tried, 
because the writer was then unknown, and nobody 
believed it possible to accomplish what he claimed. 
More recently, when it became generally known that 
such photographs were being made, and the correct- 
ness of the writer's claims was established, attention 
was diverted from the chlorophyl process by the dis- 
covery of means for producing red- and orange-sensi- 
tive gelatine dry plates, which it was believed would 
soon be made to give equally correct photographs, with 
very much shorter exposures, and without the necessity 
of preparing them immediately before use. Makers of 
gelatine dry plates privately advised photographers 
not to try the collodion color-sensitive processes, be- 
cause they expected to soon supply dry plates which 
would be much more satisfactory. Another year has 
passed, and although some good work has been done 
with color-sensitive gelatine dry plates, no American 
manufacturer has yet placed them on the market, and, 
according to all accounts, their production is attended 
with extraordinary difficulties and uncertainties; nor 
does it appear to have been proved that the best of 
them are much superior in color-sensitiveness to the 
writer’s perfected chlorophyl-eosine process, which offers 


il PREFACE. 


the advantage that it is immediately available to every 
practical photographer in the land. 

A knowledge of these facts is now causing many 
photographers to seek to know more of the chlorophyl © 
process; the collection of articles herewith reprinted 
will supply the desired information. The most impor- 
tant practical information for the working photographer 
will be found on pages 14-16, 18; but asa general 
knowledge of the subject will prove useful, all the first 
part of the book should be read carefully. Much mat- 
ter which might otherwise have been thrown out, has ~ 
been retained because of its historical value, and will 
serve to show the development of the process from the 
time chlorophyl was first used for the purpose of mak- 
ing correct-color-tone photographs. 

The writer wishes to have it clearly understood that 
while his processes will give as perfect results as any, 
he does not doubt that red-sensitive gelatine dry-plates, 
if sufficiently good and reliable ones shall be placed on 
the market, will offer important advantages for some 
purposes,—especially for use by amateurs who do not 
prepare their own plates and are not practically famil- 
iar with the collodion processes, and for landscape 
photography. But he believes that his process with 
chlorophyl also possesses peculiar merits which make 
it distinctly the best for some purposes. 

In order to make it convenient for photographers to 
try the process, the writer will undertake to supply, at 
a reasonable price, sample lots of the bromide emul- 
sion, and suitable color-screens. Photographers who 
make their own emulsion are requested to see that it 
works clear by itself, before trying it with chlorophy] ; 
an emulsion may fog when new, but work clear when 
a few days old. Fam 

Philadelphia, April 15, 1886. 


Peete ROMATIC PHOTOGRAPTY* WIT EH 
CHLOR CR ENT. 


eee fF IVES’ ORIGINAL PUBLICATIONS. 


ONT PHOTOGRAPHING COLORS. 


[THE FIRST PUBLISHED PROCESS OF PHOTOGRAPHING ALL COLORS CORRECTLY. | 


from The Philadelphia Photographer, December, 1879. 


Every photographer is acquainted with the fact that colors which 
look light will often photograph dark, while some colors that look 
dark, photograph light. But I believe very few are aware of the fact 
that it is quite possible and practicable to overcome this difficulty 
where short exposures are not essential. Such a method is very valu- 
able for copying oil paintings, and I use it to great advantage in 
making negatives of highly colored prints and objects for photographs 
on wood, where it is important that the details be very fine throughout. 

Negatives of natural scenery, made in this way, are indescribably 
beautiful; the details develop richly throughout everything, whatever 
the color. 

Hoping it may prove useful to others as it does to myself, I will 
describe the method which I have perfected. 

I place the object to be photographed in a strong light if possible, 
and use a quick-working objective, directly in front of which is placed 
a lantern-tank, having thin plate-glass sides nearly half an inch apart. 
Fill the tank with a solution of bichromate of potash, 1 part bichro- 
mate to 1,000 parts water. . Focus as usual; then prepare a plate with 
Newton's Emulsion (I always manufacture it myself, and find it 
uniform and perfectly reliable,) as follows: 

As soon as the emulsion is set, pour upon it a little alcoholic solu- 
tion of chlorophy/ (formula below), and flow backwards and forwards 
for about thirty seconds, after which wash until smooth. Flow with 
tea organifier (tea 14 ounce, water ro ounces,) rinse, and expose 


2 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


about two and a half times as long-as is required with the plain emul- 
sion without tank of yellow. 

Develop with the sal-soda developer (I make this double the 
strength reeommended by Mr. Newton, and dilute where over-expos- 
ure is suspected.) If the bichromate of potash solution is too intense, 
blue and green will photograph too dark; if it is too weak, red will 
photograph too dark. I have given the proportions I find perfectly 
adapted to my tank, lens, and chemicals. 

To-prepare the chlorophy], first extract everything soluble in water 
from myrtle or tea leaves, by treating with a number of changes of 
hot water. ‘Then dry the leaves, and the chlorophyl may be extracted 
at any time by treating about an ounce of leaves with four ounces of 
hot alcohol. 

Myrtle leaves yield the most chlorophyl, the solution of which 
should be of a deep, pure green color, and will remain good a long 
while 2/ kept 2n the dark. It spoils very soon if exposed to a strong 
light. 

In making Newton’s emulsion, I find it advantageous to mix it in 
the morning. Trya plate once each hour after, and add the chloride as 
soon as it fogs, which is sometimes within three hours. The emulsion 
will then be good at once, and remain so. Be careful to give full 
exposure. Better over- than under-expose, and judicious development 
will make perfect. 

The lantern tank which I use is a ‘‘sciopticon-tank,’’ made to 
order with plate-glass sides; it cost $1.25. Nothing could be better. 

I have made two negatives from a highly colored chromo-litho- 
graph, one by the usual method, the other by the method described 
above. The difference is wonderful. The effect in the first is hard 
and unsatisfactory, the gradations of light and shade all wrong. The 
second is remarkably soft, delicate, and brilliant; the colors photo- 
graph harmoniously, and nota detail is lost. The value of this method 
for making copies of oil paintings will be readily appreciated. 

FRED. E. IVES. 


EOSINE AND OTHER STAINED PLATES. 
from The Photographic News, Nov. 23, 1883. 

It may interest you to know of my experience with eoséme as a 
sensitizer of silver bromide for yellow light. I have used it only with 
collodio-bromide plates, but with great success. I believe that the 
action of the eosine is purely chemical, and that nothing depends 
upon the coloration of the film. I found that the application of a 





BYE. 1TVES’ “ORIGINAL PUBLICATIONS. 3 


very dilute solution was best, but that even then the sensitiveness (to 
yellow) was enormously increased by carefully washing out as much 
as possible after it had had time to act on the silver bromide. I 
applied the eosine solution (simple solution in water) after the plate 
was coated and washed, then washed again to get rid of color. A 
curious fact is that these plates showed no sensitiveness to yellow light 
when developed with the alkaline pyro. developer, unless there was 
present a little free silver nitrate.* With oxalate [of iron] develop- 
ment the presence of silver nitrate was unnecessary and undesirable. 
I used the plates immediately after their preparation, without drying. 

A much better color sensitizer (when it can be obtained) is a fresh 
alcoholic solution of chlorophyl from fresh blue-myrtle leaves. It 
should be applied as soon as the emulsion (collodion) is set, flowed 
backward and forward for thirty seconds, then the plate washed in 
water until smooth, when it is ready for exposure. 

These plates are quite sensitive to every color which can be dis- 
tinguished by the eye, including the deepest ruby red. By means of 
these plates and colored screens I have secured results which you 
would probably have thought it impossible to secure by any photo- 
graphic process. I have not been able to secure a chlorophy! solu- 
tion which would give the same results from any other leaves than 
those mentioned—‘‘ blue-myrtle ;’’ and both leaves and solution must 
be fresh to secure the greatest degree of sensitiveness. I do not see 
how it will be possible to employ chlorophyl successfully with gelatine 
plates. + FRED. E. IVES. 





*[This is true only of eosine plates prepared exactly as here indicated. If 
there be present any free eosine, it will act much like a trace of silver, to make 
the color-sensitiveness manifest itself with alkaline pyro. development, but with 
this important difference, that the trace of silver acts far more powerfully and 
perfectly than the free eosine. The plates prepared by washing out the free 
eosine and then adding a mere trace of silver nitrate are as sensitive, and will 
give as good results, as those prepared by the ‘wet eosine process” which Dr. 
Vogel published in the year following. Zhe procedure may be varied by dipping 
the washed eosine plates into an ordinary negative silver bath before exposure, and 
developing with the usual bath plate developer.. Plates prepared with eosine in 
this manner are considerably more sensitive to yellow-green than chlorophyl 
plates prepared with an o/d solution of chlorophyl]; they are therefore very useful 
under some circumstances,—as when fresh chlorophyl cannot be obtained, and 
red-sensitiveness is not required. They are very much cheaper, and for many 
purposes better, than the yellow-sensitive gelatine dry plates now in the market. | 

+[In December, 1885, I succeeded in making gelatine dry plates color-sensi- 
tive by treatment with chlorophyl. Carbutt’s B plates were soaked in water one 
minute, drained, backs wiped dry, then immersed in the alcoholic solution of 


4 ISOCHROMATIC PHOTOGRAPHY, WII CHLOROPHYL. 


ISOCHROMATIC PLATES BY MEANS OF CHLOROPHY?: 
From The Photographic News, Sept. 5, 1884. 
My method of preparing chlorophyl solution and using it for in- 


ereasing the color-sensitiveness of silver bromide plates, was published 


nearly five years ago in the Philadelphia Photographer; but in answer 
to your request, I furnish the following particulars for publication in 
the Mews. 

Take fresh blue-myrtle leaves, cut them up into very small bits, 
and place in a florence flask. Cover with alcohol, and warm over a 
spirit lamp for about twenty minutes, stirring constantly, and taking 
care not to heat too hot, which might destroy some of the chlorophyl. 
The solution will be of a deep rich green color, and will keep some 
weeks if tightly corked, and not exposed to light. It may also be 
prepared from the dried leaves by first soaking them in distilled water, 
but is not so good as that from the fresh leaves, and in either case a 
fresh solution will give the best results. I have been told that the 
addition of a little powdered zinc to the solution will cause it to retain 
its strength indefinitely, but I have not yet tried the experiment. 

I believe that any good collodio-bromide emulsion will answer, 
but I have always used one made with a slight excess of nitrate of 
silver, which was afterwards converted into chloride of silver. 

The plates are prepared by first flowing with the emulsion, then, 
as soon as it is set, covering with the chlorophyl solution for one 
minute. ‘They are then washed thoroughly with pure water, and ex- 
posed in the camera while still wet, using a colored screen in front of 
the lens to filter out light which would otherwise produce too much 
effect. As long exposures are necessary, it is often an advantage to 
flow the plate with glycerine, and the object to be photographed 
should be placed in direct sunlight, when practicable. 

The best screen for filtering the light is a small plate-glass tank 
containing a solution of bichromate of potash. If the tank is three- 
eighths inch between the glass, the bichromate solution may be of the 
strength of one grain of bichromate of potash to two ounces of water. 
If stronger, blues will photograph too dark, and yellow and red too 
light; if weaker, blues will be too light, and yellow and red too dark. 
If a solution of aniline red is used as a screen, the red and yellow of 





chlorophyl two minutes. When these plates were exposed immediately after 
their preparation, through a deep orange screen, good results were obtained,—but 
not so good as with the collodion emulsion plates. Within a few hours after their 
preparation, every trace of color-sensitiveness disappeared. | 


—— 2 





POE IVES’, ORIGINAL PUBLICATIONS. ; 5 


a highly colored chromo-lithograph can be made to photograph almost 
like white, while blue comes out black. With a green screen of a 
certain shade and intensity [chlorophyl solution, ] I have made bright 
chromo-lithographs photograph as if almost all of the color had been 
bleached out of them. . 

Something depends also upon the developer, some developers 
bringing out the color-sensitiveness more than others, or in different 
proportions; but so far as my experience goes, this difference is not 
nearly so marked with chlorophyl as with eosine plates. 

It has been stated that isochromatic plates do not give a sensibly 
different effect from others in photographing landscapes, but this is 
true only when no colored screen is employed. Some of the most 
striking results I have obtained were landscape photographs made with 
the chlorophy! plates. The effect is not only different, but so very 
different that everyone who sees them is astonished. I will send you 
prints from three negatives which were made simultaneously, one with 
chlorophyl and a red screen, one with eosine and a yellow screen, 
and one with plain emulsion and no screen. Had I used the chloro- 
phyl plate with a yellow screen, it would have given nearly the same 
result as the eosine, except that reds would have developed stronger ; 
but had I used the eosine plate with the red screen, it would have 
given no image whatever. : 

I have experimented with the addition of both chlorophyl and 
eosine to the emulsion, but have not secured one-half as good results 
in that way as by applying them in the manner which I have described. 

FRED. E. IVES. 


PoecikOUMATIC PLATES WITH CHLOROPHYLL. 


from The Year-Book of Photography for 1885. 

The method of isochromatic photography which I published in 
1879, was so great a step in advance of anything then known, that 
my claims were regarded as too improbable to merit respectful con- 
sideration, and I could not persuade anyone to give the method a 
fair trial. Writers continued to lament that ‘‘it was impossible,’ 
etc., and it was not until early in the present year, when Dr. Vogel 
claimed that he had just discovered the first and only completely suc- 
cessful method, that considerable attention was given to this line of 
research. Dr. Vogel was undoubtedly the first to suggest the use of 
dyes for increasing the color-sensitiveness of silver-bromide, but he 
was not the first by several years to publish a practically useful process, 


6 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYLL. 


nor has he, or anyone else, ever published one equally as successful 
and valuable as that which I published in 1879. 

After testing the recently-published processes, I once more called 
attention to my method in the Photographic News, Sept. 5, 1884; 
and in order that its value may be readily appreciated I now con- 
tribute to the Year-Book two photo-typographic prints illustrating its 
remarkable capabilities. The subject selected is a highly-colored 
chromo-lithograph of a lady wearing a bright-scarlet hat with purple 
feather, a yellow-brown cape, and a dark-blue dress. Having used a 
deeper yellow screen than was necessary, I have exaggerated the effect 
so that there can remain no doubt whatever of the capability of 
the process to bring out the full values of all those colors which photo- . 
graph too dark by the ordinary methods. ; 

A characteristic of my process, which distinguishes it from all 
others, is the great sensitiveness of the plates to every part of the vis- 
ible spectrum, which makes it. possible to secure an almost endless 
variety of effects by simply changing the color and intensity of the 
screens. 

The process consists of treating collodio-bromide emulsion plates 
with the chlorophyl of ‘‘ blue-myrtle’’ leaves to render them sensitive 
to all colors, then placing a yellow screen in front of the lens to cut 
off part of the blue and violet light. 

To prepare the chlorophyl, cut the leaves up fine, and cover with 
pure alcohol, heating moderately hot for a few minutes. It is most 
sensitive when fresh, but will keep good for some weeks in a cool 
place, protected from light. The leaves should be left in the solu- 
tion, and the addition of a little powdered zinc appears to have a 
beneficial effect. 

To prepare the plates, flow with collodio-bromide emulsion, and. 
when set, cover for a few seconds with the chlorophyl solution, after 
which wash in distilled water until smooth. Great care must be taken 
to protect them from light during and after preparation. | 

In front of the lens place a small tank having plate glass sides, 
and filled with a solution of bichromate of potash. If the space be- 
tween the sides of the tank measures three-eights of an inch, the 
bichromate solution may be of the strength of one grain to two ounces 
of water. If yellow and red photograph too light, the yellow solution 
should be made weaker. 

Expose two or three times as long as would be necessary if there 
were no colored screen, and develop with alkaline pyro. developer. 
If the plates veil, add more bromide to the developer, and use less 
light in the dark-room. In very warm weather the plates may not 





F. (E: IVES’ ORIGINAL’ PUBLICATIONS. 7 


work perfectly clear unless the chlorophyl solution is made a few days 
before the plates are prepared. FRED. E. IVES. 


ISOCHROMATIC PHOTOGRAPHY. 


Read at meeting of Franklin Institute, March 18, 1885. 
Published in Franklin Institute Journal, May, 1885. 


It is well known that the ordinary photographic processes do not 
reproduce colors in the true proportion of their brightness. Violet 
and blue photograph too light; green, yellow, orange and red, too 

‘dark. Fora long time it was believed to be impossible to remedy 
this defect; and even when it became known that bromide of silver 
could be made more sensitive to yellow and red by staining it with 
certain dyes, the subject received very little attention, because it was 
also known that the increase of sensitiveness was too slight to be of 
practical value in commercial photography. 

Dr. H. W. Vogel, who was one of the first, though not the first, 
to devote attention to this subject, announced, in 1873, that he had 
succeeded in making a yellow object photograph lighter than a blue 
or violet one, by using a silver-bromide plate stained with coraline, 
and exposed through a yellow glass. The plate showed no increased 
sensitiveness to red, and the experiment, although of considerable 
scientific interest, did not indicate a practically useful process. 

In the spring of 1878 I became interested in this subject, and tried 
to discover a method of producing plates which should be sensitive to 
all colors, and capable of.reproducing them in the true proportion of 
their brightness. . 1 commenced by trying nearly all the color-sensi- 
tizers which had already been suggested, in order to learn which was 
the best, and then, if possible, wy it was the best, as a guide to 
further research. Chlorophyl was the only thing I tried which was 
sufficiently sensitive to red to offer any encouragement in that direc- 
tion; but the solution which I obtained was weak and unstable, and 
far from being a satisfactory color-sensitizer. Hoping to obtain a 
better solution with which to continue my experiments, I made ex- 
tracts from many kinds of leaves, and found that a solution from blue- 
myrtle leaves looked better and kept better than any other, and when 
it was applied to the silver-bromide plates they became remarkably 
sensitive, not only to all shades of red, but also to orange, yellow and 
green. By placing in front of the lens a color-screen consisting of a 
small glass tank containing a weak solution of bichromate of potash, 
to cut off part of the blue and violet light, I obtained, with these 


8 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


chlorophyl plates, the first photographs in which all colors were 

reproduced in the true proportions of their brightness. But my chief 
desire at that time was to realize a method of producing from any 

object in colors a set of three negatives, in one of which the shadows 

should represent the blue of the original, in another the yellow, and 

in another the red, in such a manner that transparent pigment prints. 
from these negatives—blue, yellow and red—would, when superim- 

posed on a white surface, represent not only the lights and shadows, 

but also the colors of the object. This had already been attempted 
by others, who failed because their plates were not sufficiently sensi- 
tive to red and yellow. 

Having succeeded perfectly in my undertakings, I published my 
discovery in 1879,* explaining how to prepare and use the chlorophyl 
plates, in connection with the yellow screen, for the purpose of 
securing correct photographs of colored objects. 

So far as I know, nobody tried the process. Nearly five years 
later Dr. Vogel announced that, after eleven years of investigation, 
he had at last realized a successful process of this character, and that 
this new process of his, was the ‘‘solution of a problem that had long 
been encompassed with difficulty.’’ This publication attracted a 
great deal of attention, and gave me occasion to again call attention 
to my process, { and point out that it was not only the first practical 
solution of this problem, but the only truly isochromatic [correct- 
color-tone] process ever discovered. Dr. Vogel’s new process 
was not only no better in any respect, but the plates were insensitive 
to scarlet and ruby-red, and therefore would not photograph all colors 
in the true proportion of their brightness. 

My method consists in treating ordinary. collodio-bromide emul- 
sion plates with blue-myrtle chlorophyl solution, exposing them 
through the yellow screen, and then developing them in the usual 


* Philadelphia Photographer, December, 1879, p. 365. 

+ I intended this publication to be a very full and explicit one, and it was 
sufficiently so to be perfectly understood by most who saw saw it; but some may 
think I did not sufficiently emphasize the importance of using the particular kind 
of chlorophyl which I mentioned. In a brief communication to the editor of the 
Photo. News, in 1883, I described some experiments with eosine as a color-sensi- 
tizer, and then called attention to the superiority of blue-myrtle chlorophyl for 
this purpose, stating that I had not been able to secure such results with any other — 
kind of chlorophyl, and that a fresh solution from fresh leaves must be used to 
secure the greatest possible degree of sensitiveness. See Photo. News, Nov. 1883, 
Pp. 747: 

{ Photo. News, London, Sept. 5, 1884, p. 566, cay Year-Book of Photography 
for 1885, p. 211: 





a 


—— 








F. E. IVES’ ORIGINAL PUBLICATIONS. 9 


manner. ‘The emulsion which I have employed is made with an 
excess of nitrate of silver, which is afterwards neutralized by the addi- 
tion of chloride of cobalt; it is known as Newton’s emulsion. I now 
prepare the chlorophyl from fresh blue-myrtle leaves, by cutting them 
up fine, covering with pure alcohol, and heating moderately hot; the 
leaves are left in the solution, and some zinc powder is added, which 
helps to keep the chlorophyl from spoiling. I have a bottle of this 
solution which was prepared about six months ago, and now appears 
to be as good as when first made.* A glass plate is flowed with the 
emulsion, and as soon as it has set, the chlorophyl solution is applied 
for a few seconds, after which the plate is washed in pure water ae 
smooth, when it is ready for exposure. 

My color-screen consists of a small plate-glass tank, having a space 
of three-sixteenths of an inch between the glass, filled with a solution 
of bichromate of potash about one grain strong. I place the tank in 
front of the lens, in contact with the lens-mount. The advantage of 
this tank and solution is that it can be more easily obtained than 
yellow plate glass, and the color can be adjusted to meet any require- 
ment. 

The plates require about three times as much exposure through 
the yellow screen as without it,f and may be developed with the 
ordinary alkaline pyro. developer. 


* I originally recommended chlorophy] extracted from dried leaves, because 
I had not yet learned how to preserve the solution for more than a few weeks,— 
and at some seasons it would be difficult, if not impossible, to obtain fresh leaves. 
The tea organifier which I recommended is also a color-sensitizer, and when it 
is used in connection with the chlorophyl] from dried leaves the plates are as sen- 
sitive as can be safely prepared and developed in the light of an ordinary photo- 
graphic “dark-room.”’ Plates prepared with chlorophyl from fresh leaves do not 
require treatment with the tea organifier to secure this degree of sensitiveness. 
Recently I have used the tea organifier and some other sensitizers in connection 
with the solution from fresh myrtle-leaves, and in this way have produced plates 
having such an exalted color-sensitiveness as to be unmanageable in ordinary 
‘*dark-room”’ light. Possibly, such plates might be prepared and developed in 
total darkness, by the aid of suitable mechanical contrivances, but I am not sure 
that they would work clear even then, because they appear to be sensitive to heat 
as well as to light. [Previous to the publication of the foregoing note, all of my 
experiments were conducted in dark-rooms which were quite unsuitable for the 
purpose, because the orange and ruby glass windows freely transmitted the red 
light to which chlorophy] plates are sensitive. The extra-sensitive plates men- 
tioned were prepared with fresh chlorophyl, eosine and tea organifier, and such 
plates can be safely prepared and developed in a special light, as I explained in 
a later publication. ] 

+ [The reader will please note that I nowhere compared the sensitiveness of 


10 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


In order to illustrate the value of this process, I made two photo- 
graphs of a highly-colored chromo-lithograph representing a lady with 
a bright scarlet hat and purple feather, a yellow-brown cape and a 
dark-blue dress. One, by the ordinary process, represents the blue 
as lighter than the yellow-brown, the bright scarlet hat as black, and 
the purple feather as nearly white. The other, by the chlorophyl 
process, reproduces all the colors in nearly the true proportion of 
their brightness, but with a slight exaggeration of contrast produced 
purposely by using a too-strong color-solution in the small tank. 

I also made two landscape photographs, one by the ordinary 
process, and the other by the chlorophyl process, exposing them 
simultaneously. In the ordinary photograph, distant hills are lost 
through over-exposure, yet the foreground seems under-exposed, and 
yellow straw stacks and bright autumn leaves appear black. In the 
chlorophyl photograph, the distant hills are not over-exposed, nor 1s 
the foreground under-exposed ; the yellow straw stacks appear nearly 
white, and bright autumn leaves contrast strongly with the dark green 
about them. . 

To test the relative color-sensitiveness of plain emulsion plates, 
plates stained with eosine, and plates stained with the blue-myrtle 
chlorophyl, I exposed one of each kind through the same yellow 
screen, giving each five minutes’ exposure, on the same piece of copy, 
which was the chromo-lithograph already described. The plain 
emulsion plate showed only the high-lights of the picture, after pro- 
longed development. The eosine plate was under-exposed, but 
brought up everything fairly well except the scarlet hat, which came 
up like black. The chlorophyl plate was over-exposed, brought out 
all colors better than the eosine plate, and gave full value to the 
bright scarlet of the hat, the detail in which was beautifully rendered.* 

Dr. Vogel advanced the theory that silver-bromide is insensitive 
to yellow and red, because it reflects or transmits those colors; and 





this process with that of the ordinary bath process, but merely indicated the rela- 
tive exposure for the same chlorophy/ plates with and without the color screen. 
In photographing an object illuminated with direct sunlight, the collodion silver- 
bromide plates prepared with fresh myrtle-chlorophyl alone, require about ten 
times as much exposure through the-yellow screen as an ordinary bath plate with- 
out the screen; but in diffused daylight the difference is very much greater. ] 
*(‘The chlorophyl plate was prepared with a fresh solution of chlorophyl from 
fresh young myrtle-leaves. If the chlorophyl solution had been a few days old, 
or had been made from washed and dried leaves, or even from fresh leaves picked 
late in the fall of the year, the plate would have required move exposure than an 
eosine plate, to bring out the yellow, green and blue portions of the picture. ] 








FY E.-1VES’ ORIGINAL. PUBLIGATIONS. II 


that it becomes sensitive when stained, because of the optical proper- 
ties of the dyes. He afterwards admitted that only such dyes as are 
capable of entering into chemical.combination with the silver-bromide 
proved capable of increasing its sensitiveness to color, but he held to 
the theory that the optical properties of the compound were the cause 
of its color-sensitiveness. i 

I have shown that the color-sensitiveness can be produced by treat- 
ment with an organic compound which has none of the optical prop- 
erties characteristic of dyes; and that chlorophyl, which absorbs only 
red light,* greatly increases the sensitiveness also to yellow and green. 
There is, therefore, good reason to doubt if the color-sensitiveness is 
ever due to the optical properties of the dye or combination. 

Attempts have been made to produce isochromatic gelatine se 
plates which, while many times more sensitive to white light than my 
chlorophyl plates, shall also show the same relative color-sensitive- 
ness. Such plates would be very valuable but for one fact: it would 
be necessary to prepare and develope them in almost total darkness. 
Gelatine bromide dry plates extremely sensitive to yellow, but com- 
paratively insensitive to red, might be used to advantage in portrait 
and instantaneous. photography, because they could be safely prepared 
and developed in red light; but when truly isochromatic [ @//-colors- 
correct] photographs are required, the time of exposure must be reg- 
ulated to suit the degree of sensitiveness to red, which cannot safely 
[in ordinary dark-room light] be made greater than I have realized 
with my chlorophyl process. FRED. E. IVES. 


ISOCHROMATIC PHOTOGRAPHY. 


Read at meeting of Franklin Institute, May 19, 1885. 
Published in Franklin Institute Journal, July, 1885. 


For the purpose of better illustrating the capabilities of my process 
of Isochromatic Photography, I have recently made a large number 
of photographs of a color-scale, which is made up of pieces of woolen 
cloth, dyed red, scarlet, yellow, green, blue, violet, magenta, etc. 
The exposures were made through color-screens, which were carefully 
selected by the aid of the spectroscope, in order that it might be 
known in each case what kind of light was transmitted. 

I have not had time to make a set of lantern positives, but will 





* [Chlorophyl shows three feeble absorption s¢77@ in the orange-yellow and 
green, a deep black band in the red. | 


12 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


show some of the negatives on the screen, and also one positive, made 
from prints which have been arranged for comparison. 

The first negative is an ordinary photograph of the color-scale, in 
which blue, violet and magenta are the only colors which photograph 
with considerable intensity. eee 

The second photograph was made with an eosine-stained plate, 
exposed through a yellow screen. Light-blue, green, yellow and 
light yellow-brown are the only colors which photograph well. 

The third photograph is by my isochromatic process, and all of 
the colors come up in approximately the true proportions of their 
brightness. : 

The fourth is one of my chlorophyl plates exposed through a scar- 
let screen, and brings out with remarkable intensity all those colors 
which have usually been regarded as non-actinic; but green and blue 
come out like black. 


Red. Scarlet. Yellow. Green. Blue. Violet. Magenta. 





In the lantern positive, seven squares are shown from each nega- 
tive, arranged for comparison. The first. row is from the ordinary 





¥. IVESE-ORIGINAL* PUBLICATIONS. 13 


photograph, the second is from the eosine plate exposed through a 
yellow screen, the third is from the isochromatic [correct-color-tone] 
photograph, and the third is from the chlorophyl plate exposed 
through the scarlet screen. These photographs tell their own story 
so far as regards the capacity of the processes; but my investigations 
have revealed some remarkable facts, which I will now state briefly, 
without entering further into the details of my experiments. 

1. Although collodio-bromide emulsion plates, stained with blue- 
myrtle chlorophyl alone are capable of photographing all colored 
objects in the true proportions of their brightness, they are far more 
sensitive to the extreme dark-red of the spectrum, below the absorp- 
tion band of chlorophyl, than to either the orange, yellow or green. 

2. All red, orange and yellow objects reflect the dark-red light 
to which chlorophyl plates are so sensitive, and bright yellow objects 
reflect as much of this light as red ones. Yellow objects photograph 
lighter than red ones by this process, because they reflect two kinds 
of light to which the plates are sensitive, while red objects reflect only 
the one kind. 

3. The sensitiveness of the chlorophyl plates to spectrum yellow 
and green may be greatly increased by treating them with the tea 
organifier, which also nearly doubles the: general sensitiveness, but 
without appearing to alter the effect in photographs made through a 
yellow screen. Ifa green screen is used, of a shade which does not 
transmit the dark red of the spectrum, the resulting photograph is 
better when the tea organifier has been used, and does not then differ 
from one made by exposing an eosine-stained plate through the same 


screen. 
4. The dark-red of the spectrum passes freely through a solution 


of chlorophyl, and through.ruby and orange glass, but is absorbed by 
common green glass, and by solutions of sulphate of copper and 
Prussian blue. 

These facts show that plates prepared with both sensitizers, accord- 
ing to my original instructions, are, strictly speaking, more nearly 
isochromatic than those prepared:with chlorophyl alone; but that in 
the production of photographs of colored objects they seldom offer 
any practical advantage, except that of reducing the exposure about 
one-half, at the expense of some extra labor and care in their prepa- 
ration and development. 

It is also evident that the safest light in which to prepare and de- 
velop chlorophyl plates is neither ruby nor orange. ‘The light which 
I find most suitable for this purpose is that transmitted by a combina- 


tion of two thicknesses of deep orange glass with one of green. 
FRED. E. IVES. 


14 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


ISOCHROMATIC PHOTOGRAPHY. 
From Anthony's Photographic Bulletin, Fuly 11, 1885. 


In response to your invitation, I now give the following additional 
particulars of my process of ‘Isochromatic Photography, a brief de- 
scription of which you have reprinted from the Journal of the Lrank- 
lin Institute. : 

The collodion emulsion with which the plates are prepared is 
made as follows: 


Material for 20 ounces— 


Alcohol, - - - IO 02. 
Ether, - - ; IO oz. 
Bromide of Cadmium, =// | )220%oR 
Anthony’s Green Label Cotton, 120 gr. 
Nitrate of Silver, — - - 300 gt. 


Dissolve the bromide of cadmium in five ounces of the alcohol, 
then add the cotton and shake well. Add all the ether, then shake 
again until all the cotton is dissolved. 

Grind the nitrate of silver in a glass mortar, and put it in a flor- 
ence flask. Pour a small portion of the remaining five ounces of 
alcohol on the silver, and heat over an alcohol lamp (stirring briskly) 
until the alcohol is saturated with silver. Pour the silver solution into 
the collodion (do this in the dark room), and shake briskly for two 
minutes. Repeat the operation until all of the silver is in the collo- 
dion; then add the remainder of the alcohol, and proceed to test for 
free silver. 

Pour a little of the emulsion on a glass, take it into white light, 
and put on a drop of a solution of bichromate of potash, which will 
produce a blood-red stain if the emulsion contains sufficient silver. 
The excess must then be neutralized by adding to the emulsion suf- 
ficient of a strong alcoholic solution of chloride of cobalt. Add a 
little at a time, until the bichromate test no longer produces a red 
stain, when the emulsion will be right. It should be kept in an 
amber-glass bottle, in a light-tight box in the dark-room. It will be 
fit to use the day after it is made, and will keep indefinitely. It 
should be shaken up about an hour before using. 

The chlorophyl solution is made by cutting up fresh blue-myrtle 
leaves, covering them with pure alcohol, and heating moderately hot. 
If it is desired to make a solution that will keep well, some powdered 
zinc or zinc shavings should be put in with the myrtle leaves before 
heating to extract the chlorophyl. Both leaves and zine should be 








F. E. IVES*-ORIGINAL PUBLICATIONS. 15 


left in the solution, and the bottle kept in a light-tight box. I have 
a bottle of this chlorophyl solution which is nearly a year old, and 
still works well, but the plates prepared with it require three or four 
times as much exposure as those prepared with a solution not more 
than forty-eight hours old. As the plates are comparatively insensi- 
tive at their best, a fresh chlorophy]l solution should be used whenever 
it can be obtained. : 

Recently, I have found some other leaves that yield chlorophyl 
equal to the blue-myrtle; but solutions from most kinds of leaves are 
not satisfactory. 

To prepare the plates, flow with the emulsion, and when set cover 
for a few seconds with the chlorophyl solution, after which wash in 
running water until smooth. If it is desired to still further increase 
the sensitiveness, the plates may be placed in an infusion of black tea 
_ for a minute or two, and then washed again very thoroughly. These 
plates must be exposed while wet, and if more than ten minutes’ ex- 
posure will be required, they should be flowed with glycerine, which 
will keep them moist for hours, without in any way injuriously -affect- 
ing them. 

A yellow screen for cutting off part of the blue and violet light 
must be placed in front [or back] of the lens, in contact with the 
lens mount. I now use films of gelatine colored with picric acid, 
and mounted with Canada balsam between two carefully selected 
pieces of thin plate glass; but, as it would not be easy for an inexpe- 
rienced person to prepare a perfect color-screen of this description, I 
recommend the lantern tank and weak solution of bichromate of 
potash, which I have already described. 

With a color-screen of suitable intensity, and a rapid rectilinear 
lens, an exposure of one to ten minutes is sufficient to make a perfect 
negative of an oil painting in direct sunlight. The alkaline pyro. 
developer may be used, with sufficient bromide to prevent fog. 

FRED. E. IVES. 


ISOCHROMATIC PHOTOGRAPHY. 


From The British Fournal of Photography, Aug. 14, 1885. 


To THE Epirors: It may interest your readers to know that I 
have improved my process of isochromatic photography, by using 
alcohol which is tinted with eosine for making up the chlorophyl so- 
lution. It is a remarkable fact that the presence of a trace of eosine, 
when applied with the chlorophyl in this manner, not only produces 


16 





‘more yellow and green censitivenens oe at the S nee 
plates more sensitive to the red pigments.  . 
pared with the chlorophyl-eosine solution and tea. or 
color-sensitizers), give me perfect photographs of a0 


ings with exposures of a minute and less. 








ISOCHROMATIC PHOTOGRAPHY WITH 
STAN GAO! cis Baal ie 


PART 17.— MISCELLANEOUS PUBLICATIONS, AND 
Wes tAPTEMENT: RELATING TO CLAIMS TO 
et Oied 1 Y. 


FROM ANTHONY’S PHOTOGRAPHIC BULLETIN, OCT. 10, 1885. 


‘Without going into the question of who first had the idea of 
making all the colors register their true gradation of light and shade 
upon the photographic plate, it certainly remains clear that Mr. Fred. 
E. Ives, of Philadelphia, was the first to realize and practically carry 
out a precess to effect the object in view. His method of doing this 
has already been described in the pages of the Bulletin. 


‘« As will be seen by referring to Mr. Ives’ original papers in the 
Bulletin, he makes the photographic plate sensitive to red and yellow 
light by adding chlorophyll, the green coloring matter of blue-myrtle 
leaves, to the film. In Europe, on the other hand, Dr. Vogel uses a 
material which he calls azaline; while Schuman, Eder and others use 
eosine, cyanin and other dye-stuffs. In all these cases—lIves’ as well 
as the others—a screen of yellow color interposed between the object 
and the sensitive plate is used to moderate the action of the blue and 
violet rays. And Ives’ plates must be developed in subdued deep 
orange-green light. 


“Tn all the processes, the examples of which we have noted above, 
we do not find the fine gradations of shade in all the colors which is 
to be noted in the examples that we have of the Ives’ chlorophyl 
process. Ina picture of an autumn landscape that we have before 
us, the contrast between the two photographs of it—the ordinary and 
the orthochromatic—is really wonderful. In the ordinary photograph 
the richly colored foliage is one uniform mass of blackness, while in 
the orthochromatic photograph the lights and shades are beautifully 


f 


18 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


preserved. In another example we have two photographs of a bank 
note, in which at first sight it would appear that two different notes 


had been photographed; while, on the contrary, the difference is 


caused by the inability of the ordinary photograph to reproduce the 
yellow and blue parts of the note in their correct value, and the 
faithful reproduction of these by the Ives’ process.’’ 


FROM THE SCIENTIFIC AMERICAN, NOV. 7, 1885. 


‘No better proof of the failure of ordinary gelatine dry plates to 
accurately register the varying intensity of different colors is found 
than when one attempts to copy a brilliant oil painting or a chromo. 
Improvements in this direction are always interesting, and to Mr. 
Fred. E. Ives, of Philadelphia, inventor of the Ives phototype proc- 
ess, belongs the credit of the development of chlorophyl as a sensi- 
tizing medium. 

‘‘We were recently shown a few comparative specimens made by 
this process, which were remarkable for their softness and the brill- 
iancy with which ordinary non-actinic colors, such as red and yellow, 
were brought out. Under each orthochromatic photograph was 
mounted an ordinary one. One of the drawbacks of the process is 
that the solution has to be freshly prepared shortly before use, and 
the exposure necessary is unusually long. 

‘In explanation of the specimens shown us, Mr. ie states that a 
wide-angle rectilinear lens with the largest stop was used. The ex- 
posure was five minutes in direct sunlight. When the picture is par- 
ticularly bright colored, only one or two minutes are necessary; but 
if, instead of a wide-angle lens, a rapid rectilinear lens is used, it is 
possible, with a brilliant light, to reduce the exposure to less than a 
minute. 

A curious fact observed was that the plates were relatively much 
less sensitive in a weak light than with bright sunlight, so much so as 
to require at least twenty times more exposure where the proportion 
in an ordinary rapid gelatine plate would not be more than four or 
five times. 

Speaking of the emulsion, he says: ‘‘ The most sensitive plates are 
prepared with a fresh chlorophyl solution, which has-been made up 
with alcohol tinted with eosine. But no eosine should be used in 
making up chlorophyl solutions which are to be kept more than a 
week, because an o/d¢ chlorophyl aOR gives more accurate photo- 
graphs when it contains no eosine.’ 

Regarding some of his recent experiments, he continues: ‘‘ Lately 


’ = 2 ‘ Ms * 
OS ee 








MISCELLANEOUS PUBLICATIONS. 19 


I have had some emulsion which would not work clear except when 
the tea organifier was used with it. I would therefore advise any who 
experiment with the process to use the tea organifier, not only be- 
cause it increases the sensitiveness to light, but because it may insure 
better results.’ 

“It is probable that the line of experiments commenced by Mr. 
Ives may be followed up by some other interested experimentalist, 
who may discover a way of making color-sensitive plates which will 
retain their sensitiveness, similar to the ordinary gelatine dry plate, 
for any length of time.’’ 


FROM THE PHILADELPHIA LEDGER, DEC. II, 1885. 


‘Mr. Ives, of this city, has obtained remarkably 
accurate tone values in photographs of colored objects. Dr. Vogel, 
of Germany, and other European photographers, have similar proc- 
esses, but Mr. Ives is an original inventor, and has succeeded better 
than any others in this particular field of photography. The difficulty 
with the process is that the time required for the exposure is greatly 
increased. ‘This is not a matter of much importance when copies of 
paintings or colored prints are to be made, or when a photograph is 
desired of a landscape from nature without moving objects; but it 
makes portraiture from the living subject, by the new process difficult, 
if not impossible.’’ 


FROM THE BRITISH JOURNAL OF PHOTOGRAPHY, JAN. 22, 1886. 


‘<So far as we are aware, very little has 
been flemé, precy. in this country with staining the sensitive 
film. : In America, Mr. F. Ives has worked very 
successfully meth chlorophyl, and some of the results that gentleman 
has forwarded to us clearly demonstrate its value in rendering color 
in its’true relation. On the Continent, we have Dr. Vogel working 
with some of the eosines, and, latterly, with ‘‘azaline;’’ Lohse with 
turmeric, Tailfer with eosine in gelatine, etc.’’ 


20 ISOCHROMATIC PHOTOGRAPHY WITH CHLOROPHYL. 


THE DISPUTE ABOUT PRI eR tia 
A STATEMENT BY THE AUTHOR. 


In 1884, more than four years after I published my original 
method of photographing all colors in the true proportion of their 
brightness, and several months after I perfected my claim by the 
publication of additional facts and experiments, Dr. H. W. Vogel 
announced that he had invented such a method, with eosine as the 
color-sensitizer. He also asserted that his method was the result of 
eleven years of patient experiment, that it was the first practical solu- — 
tion of this problem, and that no other similar method had been pub- 
lished. I then called attention to my own earlier publications, and 
to the fact that my method with chlorophyl would give better results 
than Dr. Vogel’s method with eosine. Dr. Vogel followed with a 
communication to the Photographic News, denying the truth of my 
assertions, as follows: 

DR. VOGEL’S LETTER. 


“In the Year Book of Photography for 1885, page 111, I find an interesting 
article of Mr. Ives, Philadelphia, on his isochromatic process with chlorophyl. 
In this article Mr. Ives mentions also my researches in the matter, and says:— 
‘Dr. Vogel was undoubtedly the first to suggest the use of dyes for increasing the 
color sensitiveness of silver bromide; but he was not the first by several years to 
publish a practical, useful process,’ etc., etc. I beg to remark as to this assertion 
of Mr. Ives that, eleven years ago, I did not confine myself to make only sugges- 
tions or spectrum photographs, but that Ishowed by experiment, already described 
in my first paper, published in the Photographische Mitthetlungen, 1873, and in 
the Photographic News, 1874, that my new process of making bromide of silver 
sensitive to the so-called non-actinic rays was of real practical value. I reproduce 
here the lines in question from my paper of 1873:—‘I took a picture of a blue 
ribbon on a yellow ground. With an ordinary bromo-iodized plate I got a white 
ribbon on a dark ground. Ona bromide of silver plate, stained with coraline, I 
could not hope to get anything, because blue and yellow rays acted on this plate 
with the same energy. Therefore, I put in front of the lens a yellow glass, which. 
let pass the yellow rays, but absorbed the blue ones, and I now obtained with 
sufficient exposure a dark ribbon on a light ground.’ 

“‘] think this picture taken in 1873, in the described manner, was the first 
isochromatic photograph taken. It may be possible that chlorophyl] (first pro- 
posed by Becquerel, 1875, for increasing the sensitiveness of bromide of silver for 
red rays,) may give better results than coraline. But surely, the chlorophyl proc- 
ess is zot the first isochromatic process? 

“ Even the modus operandi of Mr. Ives is not new. Mr. Ives soaks bromide 
of silver plates in chlorophy] solution, Exactly the same method of preparation 
I employed in 1876 (Photographische Mitthetlungen, xii, page 286), and I recom- 
mended it for all dyes which are affected by free acid in collodion.”’ 








THE “DISPUTE ABOUT * PRIORITY, 21 


I replied at length to the above, but the following brief statement 
of facts covers the main points: 

1. The claim that he regarded the coraline process as ‘of real 
practical value’’ is met by his own contrary statement, in the Phofo- 
graphic News, March 28, 1884, page 195, that his early experiments 
‘““were of merely scientific value for spectrum analysis,’’ etc., etc. 
That it has no practical value is proved by his admission that coral- 
ine plates are about ezght times less color-sensitive than eosine plates, 
and not sensitive to red. — 

2. I never claimed to have published ‘‘the first isochromatic 
process,’’ but only to have published the first practically useful one, 
and the first method of photographing all colors correctly. 

3. Dr. Vogel did not use blue-myrtle chlorophyl, did not say 
that he had ever exposed any kind of a chlorophyl-stained plate 
through a color-screen, did not say, and did not know or believe, 
that it would be possible in any way to obtain correct-color-tone 
photographs by the aid of chlorophyl. So far from having discovered 
the capabilities of chlorophyl, his references to it were calculated to 
produce the impression that, so far as he knew, it was not even much 
better than coraline, and was worthy of no comparison with eosine ! 

After the appearance of my article in the Journal of the Franklin 
Institute, May, 1885, Dr. Vogel wrote other letters attacking me and 
my claims. Under pretence of correcting mistakes, which he falsely 
accused me of making, and by emphasizing the fact that one of my 
incidental remarks which was substantially correct was not exactly so, 
he tried to cast discredit on my claims by producing an impression 
that I was ignorant of the subject, and of what had been done by 
others; he not only tried to make it appear that I said what I did 
not, but at last he took refuge (?) in a positive denial that he had ever 
spoken or published certain significant statements which appeared over 
his signature in the British photographic journals. 

My only object in calling attention to these facts is to protect my 
reputation for veracity, which Dr. Vogel appeared to be trying to 
make a show of breaking down. ‘The letters referred to, and my re- 
plies to the same, may be found as follows: 


DR. H. W. VOGEL. F. E. IVES. 
Phila. Photog’r, July, 1885, p. 204. Phila. Photog’r, Sept., 1885, p. 304. 
es ae Nov. 34 \p.2304. ‘ Hy Dec., 1885, p. 384. 


Photo. Times, Nov. 13, 1885, p. 644. 
Photo. Times, Jan. 15, 1886, p. 42. § Guar Feb. 5; 1950) p67. 


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